Separation of organic nitrogen compounds from admixture with hydrocarbons



Feb. 16, 1960 SEPARATION OF ORGANIC NITROGEN COMPOUNDS FROM Filed Nov.26, 1956 R. N. FLECK ETAL 2,925,380

ADMIXTURE WITH HYDROCARBONS 2 Sheets-Sheet l 477dl/ViK Feb. 16, 1960FLECK EI'AL 7 2,925,380 I I SEPARATION OF ORGANIC NITROGEN COMPOUNDSFROM I ADMIXTURE WITH HYDRQCARBONS Filed Nov. 26, 1956 2 Sheets-Sheet 2.5126- 4. I y zzzyzz-l wa-x/r,

2 ,925,380 SEPARATION or oRGANic mnwcrn' ycoM- rouigmsFROM'ADMIXTUREiWITH'HYDROCAR- 'BON I I "droc arbon feed-stocks inrefining processes and ifromthe I products produced- 'For example, acidtreating with dilute Raymond N. Fleck, whi t' tierii and Carlyle G.Wight,

Fullerton, Calif.,"ass ignors to Union Oil Company of California, LosAngeles,TCalif., a corporation of California o I Application November26, 1956, Serial :No. 624,238

17Clainis. (C1. 208%154) 1 This invention relates to the r efi'ningofhydrocarbons,

particularly those contaminated with organic nitrogen compounds. Suchhydrocarbons include those which are produced as petroleum, such as'coal tar oil fractions and shale oils among others. 7 1 d Y 3' Manycrude petroleum streams iajre found to con t'a in in addition to theprincipal hydrocarbon constituen tsTcon- -siderable quantities oforganic nitrogen omponnds. In some cases the incidence of these nitrogenc'ornpounds is sufficient that the nitrogen content r unsas by weight.California crude oils in cases average 0.5 byweight of nitrogen. MeXican' and Venezuelan crudes have nitrogen contents about 0.2%

to about 0.35% by weight. Extensive analyses of these.

sulfuric acidforms water solublesaltswith the basic nitrogen compounds,i.e. the nitrogenbases, or the amines.

It-is other-wise ineffective, with respect to the nonbasic nitrogencompounds; Catalytic hydrogenation is effective 'to remove ,most all ofthe nitrogen compounds, but, in

order to reduce their incidenee inithe hydrogenateud prod- .uct to alevel which does not -adversely ette'cta'platinutn catalyzedreformingprocess (for gasoline,v hydrogenation pressures of the order of5,000 psi. and higher; are re-' quired. Treatmentpf such-materials withfullers earth e o educ tha ant y p nitrp en ssamp nds-rbut thisinvolvesa relatively high liquidyieldploss through retention: of hydrocarbonsonqtheadsorbent and fthe n n F II PQU ld a e s through; d p a 9 f athespent adsorbent. Furthenflit is seldomvifever possible in this' waytoreduce the"nitroge n; contamination suifi- :ciently to avoid platinumcatalyst poisoning-p The present invention is directedito, a highlyetiicient and improved process for 'remoyingf-all, and recovering mostofthe basic and'nonbasicnitrogen compounds from petrolenm, coal tar,'andshale'oil crudes,*dis tillatesvand 3 La er a qns, i M

-It'is -';a primary lobj ect of this inyention toproyide an improvedprocess for the denitrogen'ation of hydro nitrogen-containing crudesindicate that much of thenitro I gen occurs in the form of aminesor theso -calle d'hitro-- gen bases. These include pyridine, quinolirie, andthe .inono, di, tri, and tetra alkylated .derivativesofthese materials.For example California kerosenefldistillate the di, tri, and tetraalkylated quinolin'es and. certain: polyalkylated pyridines are .found.There is however considerable nonbasic nitrogen present in thesematerials; Coal tar oils produced in the coking of coal containextensive quantities of nitrogen bases and "these are principallyaromatic amines and heterocyclic nitrogen compounds. Shale oil producedby the heating'aridfrtorting of shale rock, such as that which is foundin Colorado of organic nitrogen compounds that the nitrogen content runsas high as about 2.5 %by weight. o v o 7 Crude petroleum, coal tar,oils,[aiid shale "oils are principal or potential sources of liquidfuels and solvents.

The presence of nitrogen compounds intheffuel or Solvent product impartsa very bad odor'to these materials. Their presence in the original oilvery adverselyaffects 1 hydrocarbon refining techniques by which thefuels" and solvents or other materials are produced. They have-forexample, a Well defined adverse effect onsuch processes as catalyticcracking, catalytic isomerization,and catalytic reforming, particularlyKplatinu'm catalyzed reforming.

The nitrogen compounds appear toj'lpe adsorbedon'the.

catalyst .and selectively deactivate its "active cracking carbonswhichare contaminated with organic nitrogen ra r d' It is a morespecific objectof .this invention to process f hydrocarbon streamscontaminated with organic nitrogen compounds by distilling the feed toproduce a plu- 'e tvf i f ac ion nt t a a pe s li contact aterial withthe feed fractions ill a sequence Qto; produce i r n q n s, o i in P e eb v 1. wl ed Y' th. n tr e mpbu r m. a re edf a an, and distilling eachetfluent' to separate the nitrogen comand elsewhere, resembles wartycrude but characterized I particularly in that it contains suchextensive quantities.

pounds from the.hydrocarbons of difierent boiling range.

I It is 'a specific object toprovide 'a process according to theforegoing object in whichthe feed isdistilled into two portions whichalternately contact the contact ma- It'is a furtherobjectjto providelinsuch alprocess for distilling thefeedfraction into a plurality of morethan two fractions, and in which thesolid contact material is contactedwith these'fractionsin a sequence of increasing average boiling point. II

provide in such 'a .process for It is another object. to

. thedi stil lation of such feed streams intoa plurality of fractionsand-contacting the even numbered fractions with :one massjof contactmaterial while contacting the odd numbere'difractions witha-separate'mass of contact ma- 'terial, each of the contacts being in asequence ot'increasingaverage boiling point. by y I V M It is also ;anobject to include in the foregoing process 7 7 the l s tep ofregenerating the contact material and ;freeing it of heavy. organienitrogen compounds bycombustion centers. In catalytic cracking, forexample," the gasoline yield may be reduced as much as 50% throughthepresence of sufiicientorganic nitrogen compounds to give the feed anitrogen content of about 0.3% by weight and reduced by 75% when thenitrogen content reaches about 0.45%. Platinum catalyzed reforming andother reforming processes in general are also advers'ely'efiected bynitrogen compounds in the feed. With halide promoted platinum catalyststhe nitrogen 'corn'pourids appear to react with the catalyst formingammonium halides which deposit in the apparatus. This 'deactivates thecatalyst and lowers the yield unless the halideiisreplenishedconadversee'fiects, repeated attempts have,

tinousuly. Because of the been'made'tb rentereins nitrb encampoundsfrdnihy l g a granular solid contact fa specific order. ,refractionationare muchmore readily freed of 'th''iorthereof in {the presence. of anoxygen-containing gas," Otherobjects and advantages of thepresentinvention will become apparent to thoseskilled in-the art as thedescription and illustration thereof proceed. H

afieflythe'present inven' ian comprises an improved denitrogenationprocess for treating one or. more hydro carbon streams derived fromvirtually any saure and whreh'arefcontainiriated with 1 organic nitrogencompounds. fI-he process consists offa combination of frac-,.ItiOriation andsolids-fluidcontact steps. In the latter step materialis'contacted in sequence th a 1 1 trogenate.

- are substantially unadsorbed. spent contact material and stripping itwith a fluid such as steam or other material, the spent solids in thisprocess ganic nitrogen-compounds present therein. The granular solidcontacting step employs a solid zeolitic metallo alumino silicatecontact material, more precisely defined and described below, which hasan extremely high affinity 1 for nitrogen compounds of the typeoccurring in hydrocarbon streams. In combination with this contactingstep the process utilizes a plurality of individual hydrocarbon streamsor a perliminary fractionation step in which a single wide boiling rangefeed stream is divided into a plurality of fractions of relativelynarrow boiling range. These individual streams are passed throughcontactfwith the solid material in a sequence. The individual effiuentsfrom the solid contact step are again fractionated to separate nitrogencompounds originating in one of the feed streams from hydrocarbonsoriginating in anotherof the feed streams, which fraction had adifferent average boiling point oris otherwise readily separable fromthe first stream. :The nitrogen compounds after treatment with the solidmaterial are thus readily dlstillablefrom the hydrocarbons present inthat particular efiiuent.

The present invention will be described in connection with thedenitrogenation of various petroleum and shale oil fractions. In thecase of the shale oil fractions, the nitrogen analysis is ordinarilyvery high and they present some of the most difficult hydrocarbonstreams to deni- The process is however also applicable to otherhydrocarbon streams similarly contaminated including those derived frompetroleum, coal and other are next contacted with the higher boilingfeed fraction.

-The nitrogen compounds present therein efiect an extremely active andrapid displacement exchange with the lower boiling nitrogen compounds onthe spent solid material and which originated in the lower boiling feedfraction. The higher boiling organic nitrogen compounds thus accumulateon the solids while the lower boiling nitrogen compounds are liberatedin the displace- This second efiiuent stream comprises ment exchange.the higher boiling hydrocarbons in admixture with the displaced lowerboiling nitrogen compounds. These are readily distillable in most casesfrom one another.

The thus treated contact material, now saturated with the higher boilingorganic nitrogen compounds, is again contacted at approximately the sametemperature with the lower boiling fractions of the feed stream. Areverse displacement exchange is effected in which the lower boilingnitrogen compounds displace the higher boiling nitrogen compoundspresent on the solids. This produces a first efiiuent stream comprisingthe lower boiling hydrocarbons, which are unaffected by the solids, andthe higher boiling nitrogen compounds displaced from the solids. Thisefliuent is also readily distillable to separate the lower boiling fromthe higher boiling materials.

The aforementioned, distillations are effected separately and eachproduces anoverhead and a bottoms product.

In the case of the first efiluent stream the overhead product comprisesthe lower boiling hydrocarbons substantially free of nitrogen compoundswhile the bottoms fraction comprises the high boiling nitrogen compoundssubstantially free of hydrocarbons. In the distillation of the second.efiluent stream, the overhead product comprises the lower boilingnitrogen compounds and the bottoms product comprises the higher boilinghydrocarbons.

' placement and exchange recycle streams pass, either in It is withinthe contemplation of this invention as applied to fairly wide boilingrange feedstocks to subdivide the feed material into a plurality of morethan two fractions and to contact fractions the specific granular solidcontact material herein preferred in a sequence whereby similardisplacement exchange phenomena occur to produce a plurality ofeffluents which are distilled as previously indicated. The sequencepreferred is that of increasing average boiling point. If desired, thesolid contact material may be regenerated by oxidation after the contactwith the highest boiling feed fraction in order that the heaviest andmost ditficultly removable nitrogen compounds may be removed. Such aregeneration is also applicable to the process in which only two feedfractions are employed in order to regenerate the granular solidsperiodically. Even in the case of a relatively narrow boiling range feedmaterial, particularly one which has a relatively high average boilingpoint, a single contact with the preferred solids to remove the nitrogencompounds from the hydrocarbons is effectively followed by aregeneration with an oxygen-containing gas to burn oif the nitrogencompounds.

The contact material employed in the process of this invention is asolid granular adsorbent having a mesh size range between about 2 andmesh or finer and preferably between about 4 and about 30 mesh in staticand moving bed contacts. It is used in the form of a dense compact bedof material through which the feed and disthe vapor phase or in theliquid phase. The process may employ the adsorbent in the form of asingle static bed of material in which case the process is onlysemicontinuous. Preferably a plurality of two or more static beds ofadsorbent are employed with appropriate remotely operable valving sothat the feed stream is passed through one or more of the adsorbers in aset while the exchange displacement stream passes through one or more ofthe other adsorbers in the set. In this case the feed and product flowsare continuous, in either the vapor or liquid phase, and either up ordown through the adsorbent. When the granular material is sufficientlyrugged physically the moving solids bed-modification may be employed inwhich flow of feed is maintained continuously through an adsorptionzone, the flow of displacement exchange fluid is maintained continuouslythrough a desorption zone, and the granular adsorbent is recirculatedsuccessively through these two zones. With the smaller sized mesh rangesof adsorbent, the material may be fluidized in and by the fluid streamscontacting it, although the compact bed modifications are preferredsince a greater number of theoretical and actual contact stages are morereadily obtained in smaller and simpler equipment.

The present invention may not be carried out with most of the commonlyavailable solid granular adsorbents. It has been found that theparticular solid materials Which are more efiicient the hydrocarbondenitrogenation process of the present invention are the natural orsynthetic crystalline partially dehydrated metallo alumino silicates.These materials must have pore sizes exceeding a minimum of 7 A. indiameter in order for the nitrogen compounds to be preferentiallyseparated from the hydrocarbons. The average composition of one typicalsynthetic zeolite having a pore size of about 13 A. is 5Na O-6Al O-15SiO It may be prepared by heating stoichiometric quantities'ofalumina and silica and excess caustic under pressure. The excess iswashed out and if desired other desired metal ions may then beintroduced by ion exchange. Part of the sodium in this material can beion exchanged with concentrated salt solutions at superatmosphericpressure and temperatures of l50-300 C. to introduce other metal ions.

The synthetic crystalline partially dehydrated metallo alumino silicatezeolitic adsorbents are presently available items of commerce marketedbyLinde Air Products Comthereby displacing the lower boiling nitrogencompounds previously accumulated, and a second efliuent is producedconsisting of the 300 F. to 400 F. boiling range hydrocarbons and the120 F. to- 300 F. boiling range nitrogen compounds displaced from theadsorbent.

second efliuent flows on through line 46, valve 18, and line 48 intosecond effluent still 24. The overhead prod- .uct produced through line50 from this still comprises the 120 F. to 300 F. boiling range nitrogencompounds and the bottoms product produced through line 52 comprises the300 F. to 400 F. boiling range hydrocar ,bons. In Figure l the twostreams flowing through lines 42 and 50 and containing the lightandheavy nitrogen compounds are shown as being combined to produce a singlenitrogen compound rich stream flowing through line 54 to production orstorage facilities not shown. If desired however, these two streams maybe produced separately. The same is true of the combined hydrocarbonstreams shown produced through line 56.

In the process of the foregoing example, the contacting temperatureemployed in zones 12 and 14 is vabout 410 F. so that each stream is inthe vapor phase. With wider boiling range materials such as thoseboiling between about 600 F. to 700 F. and higher, this constantadsorption temperature characterizing the process of this invention maybe effected at temperatures below the normal boiling point of thehighest fractions by passing these streams at reduced pressures incontact with the adsorbent. For example, a wide boiling range shale oilcoker distillate boiling between about 120 F. and 600 F. is readilyprocessed according to the process of this invention-at about 403 F. Thefeed stream is distilled into three fractions. The first fraction boilsbetween about 120 F. and 400 F. and is contacted with a 13 A. adsorbentat 403 F. in the vapor phase under normal atmospheric pressure. Thesecond fraction boils between about 400 F. and 500 F. and is contactedin the vapor phase at the same temperature at an absolute pressure of0.285 atmosphere. The third fraction boiling between about 500 F. and600 F. is contacted at this same temperature at a pressure of 0.047atmosphere.

Referring now more particularly to Figure 2, a modificationof theprocess shown in Figure 1 is illustrated employing the same feed still10, first effluent still 22, second eflluent still 24, but in which thestatic beds of 13 A. adsorbent employed in vessels 12 and 14 have beenreplaced with a recirculated downwardly moving bed of the same materialmaintained incontacting column 60. The feed stream is againintroduced'through line 26 and valve 28 into feed still which produces alight overhead distillate fraction through line 30 and a heavier bottomsproduct through line 32. The first effluent is again passed through line38 into first efliuent still 22 and produces the light hydrocarbonfraction through line 40 and heavy nitrogen compounds through line 42. 1The second efiluent stream' is again passed through line 48 into secondeffluent still 24 which produces the light nitrogen compounds as anoverhead product through line 50 and the heavy hydrocarbons as a bottomsproduct through line 52.

The modification here lies in contacting column 60- in which the 13 A.granular solid adsorbent is recirculated through column 60 by means ofany form of suitable conveyor 62. The solid material is introduced atthe top of the column 60, and is removed from the bottom of the columnafter passing downwardly successively through first seal streamdisengaging zone 64, first eflluent disengaging zone 66, firstcontacting zone 68, first light feed engaging zone 70, second sealingzone 72 including second sealing gas engaging zone 74,secondefiuentdisengaging zone 76, second contacting zone 78 and secondfeed fraction engaging zone 80. r s

g The first feed fraction flows through line 30 upwardly through firstcontacting zone 68 in which the light nitrogen compounds are retained byand the heavynitrogen This compounds are displaced from the 13 A.adsorbent into admixture with the unaffected light hydrocarbons toproduce the first effluent flowing through line 38. The solids nowsaturated with light nitrogen compounds move downwardly into and throughsecond contacting zone 78. Here they are contacted by the heavy orsecond feed fraction. The heavy nitrogen compounds preferentiallydisplace and are exchanged for the light nitrogen compounds,thereby-producing the second eflluent comprising a mixture of the heavyhydrocarbons unaffected by the solids and the displaced light nitrogencompounds. These two streams are distilled individually as in theprocess illustrated in Figure l. The solid adsorbent removed from thebottom of the column is saturated with heavy nitrogen compounds. Suchsaturated adsorbent is .deliveredinto first contacting zone 68 inwhichthe'heavy nitrogen compounds are displaced in exchange for the lightnitrogen compounds in the first or light feed fraction. 1

In order to prevent contamination of the first and second effluentstreams, a first seal stream is removed from disengaging zone 64 andpumped by means 82 through line 84 and valve 86 into first feed fractionengaging zone 70. Similarly a second seal stream is pumped by means 88from second disengaging zone 74 through line 90 into this same engagingzone.

Referring now more particularly to Figure 3, a somewhat more complexmodification of the present invention is shown in which a relativelywide boiling range feed stream of hydrocarbons contaminated with organicnitrogen compounds is introduced through line at a rate controlled byvalve 102 into feed still 104. Herein the wide boiling rangehydrocarbons are distilled into a plurality of four fractions. The firstand lowest boiling rangefraction is produced as an overhead distillatethrough line 106. The second or next higher boiling fraction is passedthrough line 103 into first side stripper in which components desired inthe overhead fraction are stripped therefrom and returned in the vaporphase to column 104 through line 112. The thus stripped next heavierfeed fraction is removed from-stripper 112 through line 114. The thirdor next to the highest boiling feed fraction is prepared from a streamflowing through line 116 from column 106 into second side stripper 118.Here components desired in the, third feed fraction are freed fromcomponents desired in the fourth or highest boiling feed fractioninsecond side stripper 118. The heaviest components so separated arereturned to column 106 through line 120 while the third feed fraction isproduced through line 122. The fourth feed fraction is removed from thebottom of still 106 through line 124.

These four feed fractions may, if desired, be processed in the manner ofFigure 1 modified to the extent that four static solids contactingvessels are provided through each of which the four feed streams arepassed in a sequence of increasingaverage boiling point. After contactof each 13 A. adsorbent bed with the fourth feed fraction, the heaviestnitrogen compounds retained are burned off through contact with anoxygen-containing gas at temperatures of the order of 700 F. to 1200 F.

In the modification shown'in Figure 3 however, this same sequence ofsolids-feed fraction contact is effected employing a single contactingvessel through whichthe 11.3 A. adsorbent is recirculated and passeddownwardly as amoving bed. Contacting column 126 is provided with solidsconveyor 127 which removes the granular adsorbent from the bottom of thecolumn and reintr o duces it at the top. The column is provided atsuccessively lower levels with first contacting zone 128, secondcontacting zone130, third contacting zone 132, fourth contacting zone140, and solids regeneration zone 142. Through regeneration zone 142 isrecirculated a gas stream comprising essentially flue gas by means ofblower144... Thisgas is passed through cooler, 146 ,to

- ingj-gassuchasair introduced through line 150. ,The net: production ofline gas is vented through line 152. g

' -zi':The.-first feed fraction passes upwardly couritercurrent upareas-mo of regenerationwand sis 115- 7 phase; Ethe "seal fluidisfapp'ropriat'ely a liquidfwhich i 's' alsoyinertand-gwhich is readilyseparable from the,

to the downwardly moving regenerated ,solidsain first contactingzone128. The,..lightest or first fraction nitrofsecond" feed fraction passesupwardly through second contacting zone 130.: The secondffiractionnitro- .gcn compounds are adsorbed displacingthe first fraction-nitrogencompounds into admixture'withlthezsecond fraction hydrocarbons formingthe secondefiluent stream in: second effiuent still. 158 toproducethezfirst fraction nitrogen compounds through line .160 as an:overhead distillate and the second fraction hydrocarbons as 'abot-,toms'product through line 162. 1 The"third-= feedf fraction introducedthrough line 122 passes.'upwardly'jcountercurrent;to .the moving solidsbedzin thirdzonelSZ. The third fraction nitogren com pounds in thisfraction displacethe" second fraction .nitrosecond feedfraction. Thiseflluent is produced through line; 162 and is introduced into ,thirdefiluent still '164.

The. second fractionnitrogen. compounds are produced as .genl compoundsare ads-orbedleaving the firstfra'ction' hydrocarbons This stream isproduced substantially nitrogen-free as a first effiuent-stream-throughline 154;

thessuperiaeent:'and siibjacent zones between which lit I introduced?'Whenthe' contact'is' conducted in the liquid 1', The spent granularadsorbent flowing from the bottom I ofcfourthzcontactingzone 1'40 passesinto solids regene'r "atiori" zone .l 42 wherein the heaviest nitrogencompounds areiburne'dl-from .the solid material. The regenerated solid'srarez retumed. as described for repassage through column 126. With.;afeed'rnaterial comprising a shale j oil coker distillate analyzing about0.22% by weight niremoved through line 156. This material; isdistilled-1 I ingzadsorbent comprises themetallo alumino" silicatehaving 13 A. pores. The first effiuentproduced directly from: i the topof column: 126 comprises a light gasolineanattogen boilingbetween-about120 F. and 500 R, the four .-feed'sfractions have boiling rangesrespectively of .mmuzor Filo 250 F.,2'50 ,F. to 325 F., 325 F. to

40min, 'andi'400rF. to 500 F. The downwardly mow lyzingiflabout 0.002%nitrogen. The bottoms product's 'from-eachoftheithree'eflluentdistillation columns comprise-1 the successively higher hydrocarboncon'stituentsof,

, the; feed fractions and these analyze respectively 0.004;

0.'005 and'0;007 nitrogen.

:If .des'ired,-'ia-.10..A. adsorbent can be substituted for j. the 13.xAgused inttheabovecxample. In certain cases itisfdes'irableto'enhancethe difierence between the boiling range of-EthenitrOg en compoundsderived from one ain't-overhead fraction therefrom through: lirie 166,and

as:-a.-.-bottoms product-.through'line-168.. 1

the-third fraction hydrocarbon constituents. are produced .,=-:Thei'heaviest or fourth. feed fraction: introduce throughline124:passesupwardly countercurrent to the downwardlymo'ving' solids; bed" in:fourth. contacting 'zone-a140.-- The nitrogen compounds. from -thefourth feed .ifraction: arerretained :by the. adsorbent and reflectively displace the' nitrogenwcdmpounds' therefrom-which originated?-in.-.the' ;thir'd feed: fraction. :uThe: fourth efilu entfiowing'ythrough linezl70icornprises thehydrocarbons lfrom thexfourthfeed. fraction in sadinixture :with the nitrogen compounds froin thethird'feed fraction: This ,r'naterriabis-distilled in :fourthetfluentrstill 172- producing thentl iirdr feed: fraction: nitrogen.compounds as an over head-ndistillate" through line. 174"and. :the"fourth feed line v v the 'foun individual hydrocarbon fractions .may 'beproduced separately if desired. They may be ccombined asindieatedrin-Figure: 3 infwhich ease =thefnitrogen corn-T poundszfrom-iall zhutsthe fourthsfeedr'fraction are? sent 140; bCIWCGIl' theindividual contactingjzones in column ffraction-hydrocarbons as abottoms. t'p'rloduct through" feed fraction and the boiling range .ofthehydrocarbon stream. in WhiCh these materials are mixed when theyarerrecovered .fromithei solid contact material; For ex I ain'ple, .inthe'proess ofFigure 3; the nitrogen compounds 'whoselboilingi points liebetweenl20 FJand 250 F. are pr'odu'ced;.in*the'second 'efliuent' withhydrocarbons boil ingtbetween' 2509B: and'325 -F. In some cases nitrogen"compounds".boilingslightly belovv250 F. are diflicultly separable-fromhydrocarbons boiling @slightly above 250 R Thiszproblem dependsupon'th'eiincidenceof various typesxiofj-nitrogen "compounds and.theirnormal boiling points; -When *such distillation..problems occur,it is de-' .sirable,to 'provide a *gap or substantial difference betweenboiling-ranges of fractions contacting the solids'in SHCCESSlOH'EEIIdTthB'PIQCCSS described in connection with Figure 4'provides an effective solution.

.In' Eigure' 4,' 'foilr'zfeed fractions are prepared in a manneridentical; to that described in connection with Figure13and are fed tothesystem, The lines through whichihcorresponding feed frrictiofnsf-aieintroduced are indicated with the same numbers asthose' in "Figure'3eSpecifically; the first or lowest boiling feed fraction is 'introducedthrough line? 106,;-thesecond or next heavier p I -.-fIn-t hismodification; there-is provided a first contactinggcolumn 200 providedwith separate. solids inlet 202 and .asecondycontacting column 204With'solids inlet 206;- Again thegranular adsorbent'moves downwardly126;r.and1at the :bottom "of regeneration "zone 142. These 4engaginggazones are essentially 1' identical and :.indicated K numeral;1823afol1owed- :bY'a'n appropriate yletter. dis-1 io hy m ncontinguishing one from.-thej other;v -A seal-fluid 'inlet line columns202iand 204,

prise; methane ethane,- propane, mixtures thereof, natural" gas carbondioxide, nitrogen; carbon-monoxide, hydro-i genitand the-dike. The:operatingqpressures of'the vari mlfixeontacting'zzonesearei controlledin conventional -waysa fraction is.-;introduced through linev 114, thethird or next '-tof the"heavi'est' feedfraction is introducedthrough-line d the. fourthgor heaviestieed fraction flows as .a moving.; bed through each contacting column, is d -respectively throughlines 208 and 210,.and is combined for regeneration in regeneration zone232.

Thepsfitrfiffonjregenerationemployed in this modifica tionei sl-identical to :thatshown and described in Figure 3.

A- suitableconveyor 214 for the regenerated solids is V provided'tqlrfiiurn these solids to the top of each of ,In thisrnoification, twodownward streams of ad-" sorbent are used. The sequence of feed mixturecon v 'ture is substantiallybelow"the initial boiling point of the nextrnixtu-re. For rnra'rnpler alternate feed fractions, in. Figure. 4, arepassed successively,intocontact with the comprises a seriesin which theend point of one mi);-

downw moving.v bedkof absorbent in first contacting b r main s ieefifmba rn melr;

the even numbered ones, are similarly'passediinto" contact-with theadsorbent in second'column 204. If desired, three streams of adsorbentmay be used and in this case the first stream of adsorbent contacts thefirst and fourth fractions, the second stream contacts the second andfifth fractions, and the third stream contacts the third and sixthfractions. Proportionally more fractions may be used if desired. Morethan three streams of adsorbent may be used, although ordinarily the twoshown in Figure 4 and hereinafter described are suflicient toobtainready efliuent fractionation.

In this manner the displacementexchange between the organic nitrogencompounds in a given feed fraction involves displacement of the nitrogencompounds originating in a feed fraction boiling considerably lower, thedegree depending upon the individual system. 'In' this way there isavery substantial boiling point difference between the highest boilingnitrogen compound displaced from the solid material and the lowestboiling nitrogen compound which displaces it. For example,-with twoadsorbent streams and alternate fraction contact, nitrogen compoundsdisplaced from the adsorbent and having normal boiling points in therange of from 200 F. to 250 F. are displaced by nitrogen compounds whosenormal boiling points lie for example between 300 F.'and 350 F. Thus thedistillation separation between the 200 F. to 250 F. nitrogen compoundsfrom the 300 F. to 350 F. boiling point hydrocarbons in a given effiuentstream is facilitated. 1

First contacting column'200 is provided with first con tacting zone 213and third contacting zone 215. Second contacting column 204 is providedwith second contact-"1;

ing zone 218 and fourth contacting zone 220. It is to be understood thatin the event the feed stream isdistilled into more than four fractionssuch as for example 6, 8, 10, etc., proportionately increased numbers ofcontacting zones are provided in the'first and second contactingcolumns, that is, 3, 4, or 5 contacting zones each. If three contactingcolumns are used, the first, fourth, and seventh are introduced into.the first column, the second, fifth, and eighth'pass into the. secondcolumn, etc. Against, suitable seal fluids are introduced above andbelow each individual contacting zone to prevent interfiow of fluidstherebetween.

In first contacting column 200 the downwardly moving metallo aluminosilicate adsorbents first contacts the first feed fraction boilingbetween 120 F. and 250 F. producing a first effiuent flowing throughline 222 and comprising only the hydrocarbon constituentsboiling'between 120 F. and 250 F. The adsorbent containing the firstfraction nitrogen compounds is then contacted in third contacting zone216 with the third feed fraction, namely that boiling between 325 F. and400 F. The 325 F. to 400 F. hydrocarbon effluent containing thedisplaced 120 F. to 250 F. nitrogen compounds is removed through line224 and is distilled in still 226. The dis: tiilation is exceedinglyeasy since the highest boiling nitrogen compound boils at or below 250F. and the lowest boiling hydrocarbon compound boils at or above 325 F.The nitrogen compounds are produced as an overhead distillate throughline 228 and the hydrocarbon ing through line 114 and the fourth feedfraction flowing.

through line 124 The second feedfraction, freed of its nitrogencompounds on the regenerated adsorbent, flows through line 232 as aproduct of the process. The second fraction nitrogen compounds withnormal boiling points between 250 F. and 325 F. are carried by theadsorbout downwardly intoifourth contacting mezzo where they-are removedfrom the adsorbent in displacement exchange for and by the fourthfraction nitrogen compounds boiling between 400 F. and 500 F; Thesenitrogen compounds are ultimately carried with the adsorbent into theregenerator and burned. The displaced 250 F. to 325 F. nitrogencompounds" and the 400 F. to 500 F. hydrocarbon eflluent flow fromfourth contacting-zone220 through line 234into still 236. Here again thedisplaced nitrogen compounds boil well below the hydrocarbon fractionand are produced as an overhead prodnot through line 238 while thehydrocarbon fraction is produced as a bottoms product through line 240.The two nitrogen compound streams may be produced separately orin'combination as shown in Figure -4 through line 242. The same is trueof the four individual hydrocarbon streams which may be produced inadmixture with each other, if desired, through line 244. T

In the present process for hydrocarbon denitrogenation with the specificzeolitic metallo alumino silicate adbsorbents having pore diameters of 7A. or greater, it has been found that the organic nitrogen compounds'arevery strongly retained by the solid granular adsorbent even attemperatures as high as about 850 F. It is therefore not alwaysnecessary-that the contact pressure be reduced in thecase of hydrocarbonfractions boiling in the higher temperature ranges. The zeoliticadsorbent can be contacted at a temperature of 850 F. with gasolinederived from raw shale oil in the vapor phase and subf stantially all ofthe nitrogen compounds are successfully removed. The spent solidmaterial is then contacted with a recirculated stream of flue gascontaining small controlled amounts of air whereby the nitrogencompounds are burned atternpera'tures of the order-of 950 F; and theactivity of the adsorbentis restored. The nitrogen compounds, whetherthey are basic or nonbasic,-are removed through treatment by the processof this invention to an extent of 99.5%. A substantially completeremoval of all nitrogen compounds is thus realized.

In the processes described and illustrated in connection with Figures 3and 4, the heaviest organic nitrogen compounds in a given series arelost by combustion when the; spent contact material is regenerated. Thematerial which is lost includes the nitrogen compounds present in thehighest boiling feed fraction which is processed 'in agivencontactingcolumn. In Figure 3 the nitrogen compounds in the fourth feed fractionare thus lost while in Figure 4 the nitrogen compounds in the second andfourth feed fractions are lost. This procedure is probably the mostpractical method of operating in those instances where the hydrocarbonfraction of-the efiluent is the most important. If the nitrogencompounds are to be used in the'preparation of solvents, syntheticchemicals; and the like and are thus worth saving, a furthermodification of the contacting systems shown in Figures 1 and 2 may beemployed. In those systems the granular adsorbent is first contactedwithone feed fraction, then with a higher boiling fraction and then withthe-first feed fraction to produce two 'efiluents which are separatelydistilled or otherwise fractionated to produce separate hydrocarbon andnitrogen compound streams. It is within the contemplation of thisinvention to fractionate wide boiling range feed materials into aplurality of more than two fractions as indicated in Figures 3 and 4, tocontact a static or moving bed of the herein definedadsorbw ent insequence with these fractions. The sequence employed is one-of anincreasing average boiling'pointas indicatedin the process described inFigure'3, but instead of regenertaing by combustion, the spent adsorbentafter contact with the heaviest feed fraction is again contacted by oneor more of the intermediate fractions having lower average boilingpoints to produce additional effluents which "are separately distilled.Finally the thus treated adsorbent is again contacted with the lightestfeed fraction, and the process is repeated.- In this 'situa" givenoperating pressure.

enumeration thennitrogen: compounds;iaretflostzqthrough the numbero'fifeedsfstreamsii zEach :efiluent is sepazlflfily distilled :to;[produce the. nitrogen; compounds -.as overhead products in the case ofthose effluents produced byrcontaeting. the adsorbenta'with. aheavierifeed vfraction tha lgit hadi1;contacted;aimmeditaelyr;-.:b.efore, rand.as. a

b toms: product'linir the; casei of 1 those-fiefiluents produced bycontacting the adsorbent. withaateed fraction of lower M nage boilin-goine than th immediately; previous Ec'ontha tn hfiu:adsorbentpmayibecontacted =with--fthe various feeds c'a'ms andawith :the; regeneration.gase's while suspended or fluidizeditaccoi'din'gi-t thefvvelliknovvnprinl- Although distillationpisrd scribed;-asytheiprocedurekforseparating the light and heavy co'nstituents'from .the vari-vlghzthmprevioilstdescmptionshas involvedthe use of the granular solidadsorbent thelformofstaticibeds and: downwardly moving beds, Jib-should;be understood a for produeingthe various feed;fractions in the firstinstance, it should "be"'understoodlthat other fraction methodsmavbesubstituted, e5g.,:solve'nt: extraction,cryfstallizationsazeotropie .disti11ation,-.=steanr strippihgfafid otherfractionation procedures; depending u on Ttl'ieknature' of thehydrocarbons and tlie nitrogen compounds contaminating the'sa'm'e:

:e'rherpmcess ofathisaiiivention rthus consists tofs anri'r n-ippgruedadeinitr'ogenationvprocessi fonncontaminatedzhydro-i washingsteps customary in prior adsorptionprocesses have been completelyeliminated. The process of this invention may be operated under pressureor under vaccarbon mixtures employing the principles'of solid ads drption and fiuid'fractionation in such a way so as to remove organicnitrogen compounds from the feed stream and whereby the ordinary heatingand gas stripping or liquid uum, and the, actual operating pressuresareactually determined by the pressure at which the 'feed' stream is,"

available and its boiling range, and whether the material being treatedis desirably in the vapor phase or the liquid phase. The properoperating pressure can be determined aitregen-rree ing the no f seejondmi x 25 Y egaarsgaeo Ithedorganicsrnitrogenacornpo o s'aidnrinturesawhiclrprocess.comprises: (=1): contactingthezfir'stfobsaidunixtures with: a solid-partially? dehydratedz'eolitiermetallo aalumino. silicate adsorbent having-1stantia'llyiuniformpores Iofat ileastabout: 7: A. :in. diameter andhavingT (adsorbed thereon the organic nitrogen com-, poundsinciden'tntoetheisecond of said mixtures, whereby the -said ladsorbed'organic. nitrog'e'rr compounds incident to said second mixture: are.replaced: by the organic nitrogen compounds-containediin' said first:mixture and there is produced 'first efliuent comprising non-adsorbedhydro.- carbon om onents'of said first mixture audthedisplaced 2-)'separatingitheorganic nitrogen compounds I dro'carbon product;- (3;).contacting'said ixture :with tlie adsorbent having adsorbeillther'e.-orga- 1 nitrogen'compounds incideritqto said. first iiiiiiturei-whe'rbyhe said ad sorlined organic nitrogen coma "saidfirs'tmixture arereplacedlbythe.

'inpounds contained in said" second d t ere is produced a secondeflluent; eompris= 'd'sorbed hydrocarbon" components of :said and the}displaced organic: nitrogen com? at gen-eonipbundsfrom said secondefiluentito produc rid (-5-) c'eutinuing-tue alternate" contacting :of:said adso'b t with said first and second hydrocarbon i 2? A "s"-'actrding t6- clainr l -wherein the said;

' first and second hydrocarbon mixtures are obtained by thefractionation of a single feed stream of relatively wide boilingrangeinto a relatively low-boiling fraction and a relatively high-boilingfraction..

3. A process according to claim 1 wherein, in steps (2) and (4) the saidseparations are effected bydistillation.

4. A process according to claim 1 wherein the amounts of said first andsecond hydrocarbon mixtures employed in steps (1) and (3) are soproportioned relative to each i other that the time required to replacethe adsorbed nitro-.

by those skilled in the art from known physical vcharacteristics of thematerials to be separated, vnamely, the

bubble-point and dew point'ofthe' hydrocarbon feed stream and the knownway in which these change with pressure. The operating temperaturesemployed in the process of this invention are also determined by the}physical characteristics of the feed streamand-the operating pressure,and also whether a vapor phase or a liquid phase operation is desired.In the complex gasoline streams the'operating temperature is largelydetermined by the dew point and the bubble point, of the stream a'ta' IFor; example, operating temperatures above the dew point will obviouslybe in the vapor phase while operating temperatures below the bubblepoint will be in the liquid phase. It is within the.

'cient to burn hydrocarbonaceous residues therefrom.

6. A process-according toclaim l'wherein the said adsorbent ismaintained in the "form of a fixed compact bed,,and said contactingsteps are. carried out bypassing contemplation of the present inventionto adsorbthe feed stream at a temperature between its bubble point andits dew point so that mixed phase contacting will be main- .tained forsome special streams. Obviouslythe feed contact maybein the vaporpbasefollowed by recycle stream contact in the liquid phase, .or'vice versa,if desired.

A particular embodiment of the present invention has i been hereinabovedescribed in considerable detail byway It should be understood thatvarious of illustration. other modifications and adaptations thereof maymade bythose skilled in this particular art without departing from-thespirit and scope ofthis invention as set ,forth' a in the appendedclaims. v a

i We claim: a

9. Aprocess according to claim 2 wherein the said." fractionation is socontrolled that the amounts of said.

1. A process for denitrogenating. two hydrocarbon mixtures, each'ofwhich contains normally incident organic nitrogen compounds, the organicnitrogen compounds contained in the first of said mixtures beingdifierent from said first and second hydrocarbon mixtures therethroughin opposite directions.

7'. Aprocess according to claim 1 wherein stepsy(1) and (3) areefiiected in first and second contacting zones,

respectively, and said adsorbent is circulated continuously andsuccessively therethrough'.

8. A process according to claim 1 wherein the diameter of the pores ofsaid adsorbent is between about 7 A. and

about 13A.

low-boiling and said high-boiling fractions are such that thetime'required to replace the adsorbed nitrogen compounds in step (1)issubstantially equal to the time required to replace the adsorbednitrogen compounds in step (3). v

10. A process according to claim 4 wherein said amounts of said firstand second hydrocarbon mixturesemployedin steps (1).and (3) arecontrolled by varying the individual rates at which said mixtures arecontacted with the adsorbent in said steps (1) and (3).

Y '11. Aprocess for denitrogenating a. plurality ofhyvdrocarbonnrixtures comprising a mixture of lowest boil-' range, amixture of highest boiling range, and at trogenjcompounds' incident: tosaid second said first mixture; ('4) separating the second'substantially nitrogen f'ree "hydrocarbon leastcne mixture ofintermediateboiling range, each of said mixtures being contaminated withnormally incident organic nitrogen compounds, which process comprises:(1) contacting the said mixture of lowest boiling range with a solidpartially dehydrated zeolitic metallo alumino silicate adsorbent havingsubstantially uniform pores of at least about 7 A. in diameter, wherebythere is obtained a lowest boiling effluent containing the nonadsorbedhydrocarbon components of said lowest boiling mixture and any nitrogencompounds previously adv sorbed on said adsorbent; (2) thereaftercontacting the adsorbent with the mixture of next highest boiling range,whereby there is obtained anintermediate boiling effluent comprising thenon-adsorbed hydrocarbon components of said mixture of next highestboiling range and organic nitrogen compounds adsorbed in the precedingcontacting step; (3). repeating step (2) until all of said mixtures ofintermediate boiling range-have been contacted with said adsorbent; (4)contacting the adsorbent with said mixture of highest boiling range,whereby there isobtained a highest boiling efiiuent comprising thenon-adsorbed hydrocarbon components of said highest boiling effluentand'organic nitrogen compounds adsorbed in the preceding contactingstep; 7 (5) regenerating the adsorbent after said contacting with, saidhighest boiling fraction; and (6) separating .the organic nitrogencompounds from each of said effluents to produce hydro: carbon mixturesof substantially reduced nitrogen content.

12. A process according to claim 11 wherein, in step (5), said adsorbentis regenerated by contacting it with [:16 an oxygen-containinggas at atemperature sufificientto burn hydrocarbonaceous residues therefrom. 13.A process according to claim ll'wherein the" diameter of the pores ofsaid adsorbent is between about 7A. and about 13 A. I I

14. A process-according to claim=11 wherein thesaid plurality ofhydrocarbon'mixtures is obtained by the fractional distillation of asingle hydrocarbon mixture of relatively wide boiling range. al

15. A process according to claim 11 wherein each' of said contactingsteps is effected in a separate contacting zone, and said adsorbent iscirculated continuously and successively therethrough. I? 16. A processaccording to claim 11 wherein, in step (5), the said adsorbent isregenerated by contacting it with at least one of said mixtures having aboiling range below that of said highest boiling mixture. a 17. Aprocess accordingto claim 11 wherein 'the pore diameter of saidadsorbent is about 13 A. 1

"References Cited in the file of this patent UNITED STATES PATENTS2,606,143 Smith et al. Aug. 5, 1952 2,763,603 Skinner ..Y Sept. 18, 19562,779,718

1. A PROCESS FOR DENITROGENATING TWO HYDROCARBON MIXTURES, EACH OF WHICHCONTAINS NORMALLY INCIDENT ORGANIC NITROGEN COMPOUNDS, THE ORGANICNITROGEN COMPOUNDS CONTAINED IN THE FIRST OF SAID MIXTURES BEINGDIFFERENT FROM THE ORGANIC NITROGEN COMPOUNDS CONTAINED IN THE SECOND OFSAID MIXTURES, WHICH PROCESS COMPRISES: (1) CONTACTING THE FIRST OF SAIDMIXTURES WITH A SOLID PARTIALLY DEHYDRATED ZEOLITIC METALLO ALUMINOSILICATE ADSORBENT HAVING SUBSTANTIALLY UNIFROM PORES OF AT LEAST ABOUT7 A. IN DIAMETER AND HAVING ADSORBED THEREON THE ORGANIC NITROGENCOMPOUNDS INCIDENT TO THE SECOND OF SAID MIXTURES, WHEREBY THE SAIDADSORBED ORGANIC NITROGEN COMPOUNDS INCIDENT TO SAID SECOND MIXTURE AREREPLACED BY THE ORGANIC NITROGEN COMPOUNDS CONTAINED IN SAID FIRSTMIXTURE AND THERE IS PRODUCED A FIRST EFFLUENT COMPRISING NON-ADSORBEDHYDROCARBON COMPONENTS OF SAID FIRST MIXTURE AND THE DISPLACED ORGANICNITROGEN COMPOUNDS INCIDENT TO SAID SECOND MIXTURE, (2) SEPARATING THEORGANIC NITROGEN COMPOUNDS FROM SAID FIRST EFFLUENT TO PRODUCE A FIRSTSUBSTANTIALLY NITROGEN-FREE HYDROCARBON PRODUCT, (3) CONTACTING SAIDSECOND MIXTURE WITH THE ADSORBENT HAVING ADSORBED THEREON THE ORGANICNITROGEN COMPOUNDS INCIDENT TO SAID FIRST MIXTURE, WHEREBY THE SAIDADSORBED ORGANIC NITROGEN COMPOUNDS CONTAINED IN SAID FIRST MIXTURE AREREPLACED BY THE ORGANIC NITROGEN COMPOUNDS CONTAINED IN SAID SECONDMIXTURE AND THEREIS PRODUCED A SECOND EFFLUENT COMPRISING THENON-ADSORBED HYDROCARBON COMPONENTS OF SAID SECOND MIXTURE AND THEDISPLACED ORGANIC NITROGEN COMPOUNDS INCIDENT TO SAID FIRST MIXTURE, (4)SEPARATING THE ORGANIC NITROGEN COMPOUNDS FROM SAID SECOND EFFLUENT TOPRODUCE A SECOND SUBSTANTIALLY NITROGEN-FREE HYDROCARBON PRODUCT, AND(5) CONTINUING THE ALTERNATE CONTACTING OF SAID ADSORBENT WITH SAIDFIRST AND SECOND HYDROCARBON MIXTURE.